KV is crashing {#0 0x00007f116996e61e in BackfillManager::moveFirstPendingToInitializing() () from /opt/couchbase/bin/../lib/libep.so}

KV is crashed while running the following test scenario:

1. create 2 buckets, 3scopes per bucket and 3 collections per scope
2. create analytics dataset on each collection
3. create a user "test_user" with role "analytics_select" and give access to bucket_1.scope_1 also to bucket_1
4. run a count query: select count from dataset_name; twice where the first query with the dataset related to bucket_1.scope_1 or bucket_2 and the second query with any dataset related to collections in bucket_2

Note that the test scenario went fine but core-dump is seen

cmd to verify on TAF: 

gradle --refresh-dependencies testrunner -P jython=/opt/jython/bin/jython -P 'args=-i /tmp/testexec.15831.ini GROUP=P0SET2,threads_to_use=10,upgrade_version=7.0.0-4617 -t cbas.cbas_collection_functional_test.CBASDatasetsAndCollections.test_analytics_select_rbac_role_for_collections,bucket_spec=analytics.multi_bucket,bucket_user=True,scope_user=True'